Cellulose esters with dimensional stability



United States Patent 2,993,749 CELLULOSE ESTERS WITH DIMENSIONAL STABILITY William G. Sloan and Arthur M. Du Pre', Jr., New 0.-

leans, La., Edmund M. Buras, Jr., Washington, D.C., and Hermann J. Janssen, New Orleans, and John D. Tallant, Kenner, La., assignors to the United States of America as represented by the Secretary of Agriculture No Drawing. Filed May 23, 1958, Ser. No. 737,456 1 Claim. (Cl. 8-132) (Granted under Title 35, US. Code (1952), sec. 266) A non-exclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all purposes of the United States Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

This invention relates to a process for producing chemically modified cellulosic textiles with dimensional stability. More particularly this invention relates to a process of heat curing under stress fibrous cellulosic esters and ethers in the form of fiber, yarns, or fabrics.

The products prepared according to the process of this invention exhibit greatly reduced growth when subjected to cyclic loading. Growth, with specific reference to dimensional stability, may be defined simply as the amount of bagginess after repeated loading to less than the breaking strength of the material (approximately /3 the breaking strength).

Growth is defined above as the displacement of the tenth cycle hysteresis loop along the elongation axis (the upper limit of the loop being /3 of the breaking strength). Dimensional stability is a highly desirable characteristic in virtually every end use to which textile materials may be put. Dimensional stability is particularly desirable in the case of chemically modified cellulosic fibers and some obvious uses of dimensionally stabilized fabrics (i.e. fabrics that will resist growth or bagginess after being subjected to stress or tension) are in conveyor belts (paper drying belts), upholstery backings, articles of wearing apparel and the like. The combined efiect of heat and tension as employed in the process of this invention does not materially impair the breaking strength of the textile material.

In general the process of this invention involves heating certain chemically modified cotton fibers in the form of yarns, or fabrics under tension. The operable temperature can vary from 100 C. to as high as 235 C., the upper practical limit being the onset of heat degradation in the material undergoing treatment. The time requirements for the treatments disclosed in this invention can vary from 30 seconds to as much as .8 minutes. The more extended heating periods are employed with the lower treating temperature. Tension (stress) in amounts approximating 50% of the original breaking strength of the materials undergoing treatment can be applied in the process. Tension approximating /3 of the breaking strength as measured under standard textile testing conditions of the mat rial is preferred.

The heat treatment can be carried out as a continuous operation or as a batch operation. The treatments described in the specific examples which follow were carried out in a small, electrically heated and controlled cylindrical oven approximately 12 inches 'long. The effective heating chamber of the oven was approximately 9 inches in length. The cylindrical oven was positioned vertically with respect to its long axis. The particular oven employed was closed at both ends with Bakelite stoppers. Each stopper was provided with a narrow slot through its center to permit passage of the material undergoing treatment. The upper Bakelite stopper in the oven was drilled for insertion of the thermometer. The material undergoing treatment was supported outside and above the oven by means of clamps. The free end was threaded through first the upper oven stopper slot then down through the oven proper and out through the lower oven stopper .slot. Through the slots and within the ovenitself, the material undergoing treatment hung free. The lower emergent end of the material undergoing treatment was loaded with weights in order to provide tension. Treatment temperatures of C., 200 C., and 235 C. were utilized along with various tensions up to 50% of the breaking strength of the .original material. Treatment time varied from 3.0 seconds to 8 minutes.

The specific examples are simple batch type processing treatments but it will be recognized that a variety of known means can be employed to carry out the treatment in batch or continuous operation. In the specific examples and in the tabular data which follow we use the term partially acetylated cotton to describe cotton that has been treated with an acetylating agent (i.e. acetic anhydride) so as to esterify part but not all of the available hydroxyl groups on the cellulose. It is possible, by the use of catalysts and specific conditions, to replace as many as three hydroxyl groups .per .anhydroglucose .unit of cellulose with acetyl groups (a degree of substitution of three). I Partially acetylated cotton, we define as acetylated cotton which has a degree of substitution of from 0.5 to 2.0 substituted hydroxyl groups per anhydroglucose unit (acetyl content .of from 12 to 35% based on the weight of the acetylated cotton). Fully acetylated cotton exhibits a degree of substitution of from 2.0 to 3.0 (acetyl content 35 to 45%).

The partially cyanoethylated cotton shown in Example 5 below, is a cotton with a degree of substitution of 1.1 to 1.3.

EXAMPLE 1 Table I.--Properties of partially acetylated 8/5 yarnsafter treatment with heat and load for 30 seconds 1 Conditions of treatment Single strand Elonga- Growth Secant Load, perbreaking tion-atafter 10 Modulus, cent of strength, break, cycles, lbs/100% Temp., 0. breaking lb. percent percent strength of control Control (no heat or load). 12.9 9. 9 1. 76 100 0 12. 4 8. 8 1. 10 141 10 18. 6 11.4 1. 20 119 30 13. 4 8.3 0.70 161 50 12. 3 6. 2 .40 198 0 13.9 10. 2 1.70 136 10 13.8 7. 8 0.50 177 30 12.0 ,5. 2 30 231 40 10. 0 4. 2 30 238 0 14.0 11.4 1. 30 123 1 13. 4 8. 2 0.80 163 2. 5 13. 7 8. 3 .80 165 5 11.8 6. 8 .60 174 10 12.9 5.0 .30 258 20 12.5 4. 9 10 255 0 12.8 9. 3 1.30 138 1 11.6 8. 2 1.20 2. 5 12.0 7. 3 0. 70 164 5 11.7 6. 6 .50 177 10 12.5 6.2 .30 202 20 10. 9 4. 5 .20 242 1 All samples were heated a total of 30 seconds with load and an additional 20 seconds without load (time necessary to apply and remove load) Samples with 0 load were heated 50 seconds.

Table II.PrpErties of partially acetylated 8/5 yarn Table II.-Efiect of heat and load on properties of fully after treatment with heat and load for 1 minute 1 acetylated 10/3 yarn Sin is Elon a- Growth Secant Oond1t1ons of treatment single 5 C at It t t bstrag tTiJon-Etafter 011 1 10115 O rea men rea g rea eye 85, S. a

strand Elonga- Growth Secant Load, perbreaking tion-atafter 10 Modulus, percent percent cent of strength, break, cycles, lbs/100% Temp, C. breaking lb. percent percent ControL 238 11. 5 29 strength 1 min. (200 Ofcontml o. 6.2 22.8 12.0 27 10 1min. load (30%) 6.7 16.8 o. 65 40 Control (no 1 min., 20 sec. heat (200 heat0r1oad) 129 99 L76 130 205 200 0 l3. 2 9. 5 2. 20 139 (L30 1 Heated 1 minute with load and an additional 20 seconds without 0 2 1 20 load (time necessary to apply and remove load). 20 12. 3 3. 8 0. 10 324 15 EXAMPLE 4 1 All samples were heated a total of 1 minute with load and an additlonal seconds without load (time necessary to apply and remove Table Efiect of heat and load propernes of fully load). Samples with 0 load were heated for 1 minute and 20 seconds. acetylated fabric XAM L 20 Breaking Elonga- Growth Secant E P E 2 Conditions of treatment strength, tion-atafter 10 Modulus lb. break,t o oios, lbs 100% ercen ercen Table I.Efiect of heat and load on propertles of partially p p acetylated fabr'c Control 152 13.1 5.08 1,160 Heated 1.5 min, 200 0-- 152 12.9 5. 00 1, 178 Lottded th breaking 154 11 8 3 65 1 305 Breaking Elonga- Growth Secant 5 Conditions of treatment strength, tion-atafter 10 Modulus i g 3 f f l;

lbs. break, cycles, lbs/100% W1 173 3 9 0 33 4 436 percent percent 03 l g p hm i; %go gg 2 5 L 84 1, 061 1 Strip breaks on 100 threads.

rnm. 8E DO 410a u n n n n 89.2 7.0 1.36 1, 274 EXAMPLE 5 K 9%, 22 g Table I .Efiect of heat and load on properties of partially 103d) 87. 0 3. 1 0. 11 2, 800 cyanoethylated yarn 1 1 Strip breaks on 96 threads. Breaking E10nga Growth Conditions 0! treatment strength, ton-zlagtafter 10 ea cyc es, EXAMPLE 3 percent percent Table I.Efiect of heat and loading for 30 seconds on 40 ggfif g g a' ;55%1553: 5

growth of fully acetaylated yarn 1 1 14/2 gray yarn 4.1 TM cyanoethylated in liquid phase.

Conditions of treatment We claim: I

G A process comprising heating cyanoethylated cotton rowth Load, per- (after 10 fibers having a degree of substitution of from 0.5 to 2.0 cent of cycles) substituted hydroxyl groups per anhydroglucose unit at a Tom C breakin ercent p strength in p temperature of from 100 to 235 C. for a period of from 30 seconds to 8 minutes While applying to the fibers 5 tension in the amount of from /3 to /2 of the breaking 11 5 0 6 65 strength of the partially cyanoethylated fibers to produce 0 5.4 dimensionally stable partially cyanoethylated cotton 10 5.0 fibers 2.0

0 8.1 g3 References Cited 1n the file of thls patent UNITED STATES PATENTS f: 2,198,660 Dreyfus Apr. 30, 1940 1 214 2,346,208 COnaWaY Apr. 11, 1944 -2 3 2,395,396 Couaway Feb. 26, 1946 10 I90 2,447,567 Dreyfus Aug. 24, 1948 2,777,750 Sprague et a1. Jan. 15, 1957 ti 1 All zsgrnplesgveregfiatidla tarsal of 30 seconds vgith load and1 an addi- ,7 Finlayson fit 2, 1 58 one. 5900!] 5 W1 011 O3 ime necessary 0 341) an remove load). Samples with 0 load were heated 50 seconds. p y 2900669 Booth 1959 OTHER REFERENCES Buras et al.: New Textile Products From Cotton, Southern Utilization Research Branch, New Orleans, La., ARS724, September 1956, pp. 1-24. 

